Human brains (and bodies) are relentless optimizers. "Use it or lose it" applies to everything from muscle tone and flexibility up to higher cognitive stuff like mathematics. The reason nothing "sticks" is because kids stop using it the moment they stop being tested on it.

We treat education like an assembly line that's supposed to turn every kid into a productive member of society, using a one-size-fits-all curriculum. That's a wrong-headed approach. We should treat it like a mix between olympic trials and career fair. Identify the precocious and the enthusiastic in each subject area. Let teens decide what they want to do.

It won't work, however, until we give teens the right to self-determination. Helicopter parents trying to force their kids to be engineers or doctors, ability be damned, is one of the most pernicious factors in the sorry state of education. The other, perhaps equally pernicious, is the parents who can't or won't help their kids with anything despite their eagerness to learn.